Results of the sequence-stratigraphic analysis of the Achimovsky deposits of the Yamburg oil and gas condensate field

Sequence-stratigraphic analysis is one of the instruments allowing increasing the accuracy of the geologic models of the clinoform thickness. This article gives an example of the sequence approach to the Neocomian stage study at the Yamburg oil and gas condensate field, which is one of the largest in the world.
Materials and methods
The basic study data were an 8368 km2 3D seismic data cube. Sequence-stratigraphic analysis was used to restore the sedimentation history of the Neocomian basin.
Results
Sequence-stratigraphic analysis carries additional information required to restore the sedimentation history. The results of the geoseismic analysis allowed the authors specifying differences between the sedimentological trends within the YOGCF. The Achmovsky deposits of the YOGCF had formed mostly under conditions of alternation of the early and late stages of the relative low stand of sea level. Highstand Systems Tract shows up only at the final stage of the Neocomian basin filling in the south part of the field.
Conclusions
Results of the sequence-stratigraphic analysis allowed clarifying regularities of the Achimovsky productive reservoirs and zones of interest within its territory. In particular, it was determined that the most important depocenters, which are sediment accumulations, are depressions or vugs between large consedimental elevations that were filled mostly by turbidite flows of the early and late stages of the low stand of sea level. The well data shows that the net reservoirs in the deep pressure sinks are over 120 m, and 70 m at the elevations.
Differences in the history of the development of certain parts of the studied territory lead to sharp seismofacial changes depending on the directionality of the paleotectonic considemintal movements and the intensity of the shelf feeding with fragmentary material. It indicates significant conventions of the global forecast of the relative sea level fluctuations based on the limited seismostratigraphic data.